Blueberries have been the subjects of several prior art processes, but to date they are available in only a few forms. All less than preferred for muffin mixes, breakfast cereals and the like. Thus, blueberries are currently considered under utilized for their beneficial healthy-diet advantages.
In U.S. Pat. No. 4,350,711, Kahn, et al., treat blueberries among other fruits. They infuse fruits with fructose sugar solids. The resulting products are said to remain non-crystalline at freezer temperatures. The fruit is infused by immersing it in two or more sugar containing solutes baths of gradually increasing sugar concentration so that the solids content of the fruit is increased in a step-wise and gradual manner to the level of about 32 to 55 percent by weight. The baths can also contain other materials such as polyhydric alcohols and texture-improving additives like low methoxyl pectin or calcium hydroxide. In the one example on blueberries, the fruit contained about 38% infused solids after soaking heated, under vacuum prior to frozen storage.
In U.S. Pat. No. 4,390,550, Kahn, et al., disclose Infusing fruit (blueberries not mentioned) with sugar solutes to reduce the water activity by creating sites for removing part of the water content and bathing the fruit in sugar bath to infuse sugar therein. The bath is a fructose-containing corn syrup of about 70 to 80% sugar solids with 40 to 90% being fructose and/or dextrose, resulting in fruit having a water activity of 0.45 to 0.65. The fruit is added to cereal.
In another approach, in U.S. Pat. No. 4,364,968, Waitman, et al., are primarily concerned with preparing a dried grape product, but mention blueberries in a long list of fruits that can be processed. Grapes are processed to remain soft with minimal color, flavor, or textural changes over extended periods of time. The process combines the use of enzyme inactivation and a hydrophilic carbohydrate infusion into fresh grapes, followed by drying the grapes to a moisture content of less than 30%. The dry grapes are then converted into simulated raisins by storing them for a period of time under conditions of controlled humidity and elevated temperature effective to provide a darkening in color and to develop a natural raisin-like flavor within the grapes without further drying.
In U.S. Pat. No. 4,103,035, to Fulger, et al., a process is disclosed to soften raisins to make them more palatable in cereal, without causing the cereal to become soggy. To do this, it had been common practice to add a humectant, but it was difficult to get the humectant to penetrate the raisins. They proposed first treating the raisins with a hot, weak acid and then washing with glycerol, sorbitol, or other humectant, followed by water washing and drying to a moisture content of about from 12% to 20%.
In another infusion process, O'Mahoney, et al, point out in U.S. Pat. No. 4,551,348, that rapidly infusing fruit with sugar solutes can be achieved in an infusion bath which is maintained at a substantially constant solutes concentration and viscosity. During the course of the infusion process infusion solution is removed, exposed to an enzyme and concentrated before returning the concentrated solution to the original infusion bath.
Augustine, et al., in U.S. Pat. No. 4,775,545, describe the preparation of a sweetened fruit having a low water activity relative to its moisture content. A dry fruit (from a long list including blueberries) is bathed in an aqueous sugar solution having about 70 to 95 weight percent sugar, at least about 75 weight percent of which is fructose. The bath preferably includes an alkaline calcium compound.
In U.S. Pat. No. 5,000,972, Nafisi-Movaghar describes a process for drying fruits that includes applying vacuum while infusing with a sugar solution containing an acid and an antimicrobial agent. The objectives seem to be centered on the prevention of enzymatic and nonenzymatic browning without the use of sulfites and blueberries are not among the fruits listed for treatment.
In U.S. Pat. No. 5,223,287, Kearns, et al., prepare dried fruits said to have improved handling and physical properties by coating the fruits with a finely-divided, specially-prepared calcium citrate reaction product. The dried fruits are suitable for use with dry cereals.
In U.S. Pat. No. 5,320,861, Mantius, et al., describe extraction, especially of firm fruit such as cranberries, of low tannin juices by using a countercurrent extractor. Reinfusion of decharacterized, extracted fruit pieces with infusion syrups, such as juices from fruits (e.g., blueberries) other than that extracted, produces fruit food products of various flavors.
In U.S. Pat. No. 5,364,643, Morimoto, et al., describe a process for infusing dried fruits by coating the dried fruits with an edible humectant-containing gel. The resulting infused products are said to be relatively undamaged and high in flavor.
In U.S. Pat. No. 5,534,280, Welch describes a process for treating a solid food product having water soluble-and water-insoluble volatile materials soluble in alcohol and ether. The process includes cutting the product into pieces, placing the pieces in a volume of water containing an anti-oxidant, and drawing a vacuum on the pieces in the water to pull air out of the cells of the pieces. The vacuum is released to cause water and the anti-oxidant to enter the cells of the pieces. The pieces are then heated to dry them and to drive off a mixture of water vapor or steam and the volatiles. The mixture is directed through an adsorbent to remove the volatiles from the mixture. The volatiles are fractionated by a complex process and at least a portion are added back to the product.
Because of the problems with packaging fruit with cereal, Walter, et al., in U.S. Pat. No. 5,718,931, describe the preparation of low-fat, coated dry fabricated fruit pieces to simulate dried fruit pieces for use as a particulate additive in a ready-to-eat cereal. The coated fruit pieces include about 25% to 50% of a low-moisture, gelled center having high humectant levels and about 50% to 75% of a base coating comprising dried fruit material in particulate form and about 1% to 10% of thin film top coat.
And, in U.S. Pat. No. 5,718,939, Nugent describes infusing sugar into fruits and vegetables by treating them with water to cause osmotic rupturing of at least a portion of the cells before infusing it with a concentrated syrup. Infusion is conducted in a stage-wise manner to result in an infused product having a Brix level from about 40.degree. to about 52.degree..
The art is awaiting the development of a process which takes into account the unique properties of blueberries and enables the production of these in a partially-dried, tender, appetizing and shelf-stable form, suitable for a variety of purposes, such as packaging with baking mixes, such as for muffins, pancakes, cakes, and the like, and with dry ready-to-eat breakfast cereals.